1 . Field of the Invention
The present invention relates to a connector for electrically connecting a chip electrode of a semiconductor element and a lead constituting an external leading terminal thereof, and a resin-sealed semiconductor device using the connector. Particularly, the present invention relates to a connector and resin-sealed semiconductor device that can be used effectively even when the area of the chip electrode is extremely small.
2 . Description of the Related Art
A resin-sealed semiconductor device such as a diode for use with high power has a large number of aluminum wires bonded together to configure internal wiring when connecting a chip electrode of a semiconductor element to an external leading electrode, the semiconductor element having anode potential and cathode potential applied onto the same plane of the semiconductor element.
FIG. 4 is a perspective view showing a resin-sealed semiconductor device completed by a resin sealing process.
A semiconductor device 1 is configured by mold-sealing a discrete semiconductor element using a package outer shape of a TO-3P, wherein internal wiring and a semiconductor chip are protected by a sealing resin 2. Prior to the resin sealing process, wire bonding is implemented in which the semiconductor chip is joined to a chip mounting part (die pad) and inner lead parts of external leading terminals 3 and the like are electrically connected to chip electrodes such as an anode electrode and a cathode electrode.
In order to achieve a high current rating in this type of semiconductor device 1, a large number of aluminum wires need to be bonded sequentially to the chip electrodes of the semiconductor chip mounted on a lead frame. However, an internal wiring method using wire bonding repeatedly performs a step of bonding the aluminum wires between an electrode on a chip surface and a lead of the package, requiring a considerable amount of processing time. Therefore, the number of bonding devices for connecting the aluminum wires increases as the production of semiconductor devices increases, lowering the efficiency in the production output per facility.
Japanese Patent Application Publication No. 2009-44107 discloses an invention of a terminal board circuit in which each lead leg of a diode is joined to a common terminal board. The terminal board circuit of this invention can ensure safety of its function without degrading its performance, even when the joint part of one of the lead legs has a defect.
Japanese Patent Application Publication No. 2009-267054 describes an invention of a semiconductor device that mainly has a semiconductor element, an island on which the semiconductor element is mounted, a metal connection plate for connecting the semiconductor element and a lead, and a sealing resin for integrally sealing these components. In this invention, when soldering or fixing the metal connection plate to the lead and the semiconductor element by means of a fixing material, a protruding portion that partially protrudes in a thickness direction is brought into contact with the lead and fixed in a state in which the metal connection plate is disposed in a predetermined position.
Each of these inventions described above adopts a wireless bonding method for connecting wires using the terminal board or metal connection plate. In other words, each of these inventions aims to improve the efficiency of producing a semiconductor device without connecting a large number of wires.
Japanese Patent Application Publication No. H7-30050 describes an invention of a semiconductor device in which a chip terminal (electrode) and an inner lead of a lead frame are connected with each other by a single wire. This invention describes the lead frame in which a pad is set below the surface of the lead. In this invention, a support bar is subjected to a half blanking process to have steps, and a pad surface on which the semiconductor chip is fixed and mounted is set below the inner lead. This facilitates the bonding work for connecting the chip terminal and the inner lead to each other by a single wire and achieves a reduction of the length of the bonding wire and the resin sealing thickness.
Incidentally, when providing wiring using a single connector instead of providing wiring having a plurality of wires, the size of an interface between the connector and a chip electrode needs to be close to the electrode surface area on the semiconductor chip as much as possible due to the significantly small electrode surface area. Furthermore, the cross-sectional area of the connector needs to be increased as much as possible to reduce a current resistance value of the connector in order to achieve a high current rating of a semiconductor device.
However, when forming a connector using a thick metal plate to obtain a small current resistance value, bending the metal plate makes the curved surface shape (R shape) thereof unstable. Moreover, it is difficult to configure the metal plate into the shape of the interface that conforms with the size of the chip electrode or the distance between the chip electrode and the lead when forming the curved surface (curved R) on the connector according to its plate thickness. For this reason, the joint between the chip electrode of the semiconductor element and the connector or between the lead (inner lead part) and the connector becomes insufficient, and the electrical connection between the chip electrode and the external leading terminals 3 and the like becomes insufficient, resulting in a decline of the yield and reliability of the resin-sealed semiconductor device.